Method and device for detecting cellular targets in bodily sources using carbon nanotube thin film

Abstract

A device and method detect cellular targets in a bodily source by utilizing a biofunctional pad comprised of a thin film of carbon nanotubes (CNT's). When antibodies are absorbed by the CNT's, cellular targets having markers matching the antibodies may be detected in a bodily source placed upon the biofunctional pad by measuring the conductivity of the thin film using conductive contacts electrically coupled to the thin film, as the binding of the receptors in the cellular targets to the antibodies changes the free energy in the thin film. In many respects, the device functions as a Field Effect Transistor (FET) with the bodily source, e.g., blood, acting as a polyelectrolyte liquid gate electrode to create a varying electrostatic charge or capacitance in the thin film based upon the binding of cellular targets in the source to the antibodies present on the biofunctional pad.

What is claimed: 
     
       1. A method of fabricating a sensor for detecting cellular targets in a bodily source, the method comprising:
 forming a thin film of carbon nanotubes (CNT's) on a carrier using vacuum filtration; 
 mechanically bonding the thin film to a dielectric layer on a semiconductor substrate; 
 separating the thin film from the carrier; 
 patterning the thin film to form a biofunctional pad; and 
 depositing a plurality of conductive contacts on the substrate, with at least a portion of each conductive contact overlapping and electrically coupled to the thin film, wherein after forming the thin film, the method additionally comprises the step of altering a surface of the thin film or the biofunctional pad, to provide the biofunctional pad with a hydrophilic surface which lowers the density of the CNTs on the portion of the surface that was altered. 
 
     
     
       2. The method of  claim 1 , further comprising annealing the substrate after depositing the plurality of conductive contacts thereon. 
     
     
       3. The method of  claim 1 , further comprising testing the IV characteristics of the sensor. 
     
     
       4. The method of  claim 1 , further comprising depositing antibodies on the biofunctional pad such that at least a portion of the antibodies are absorbed by the thin film of CNT's. 
     
     
       5. The method of  claim 4 , wherein depositing the antibodies is performed either during fabrication of the sensor or during clinical use of the sensor. 
     
     
       6. The method of  claim 1 , wherein the cellular target comprises a cancer cell, and wherein the bodily source comprises a drop of blood. 
     
     
       7. The method of  claim 6 , further comprising depositing a layer of antibodies on the biofunctional pad, wherein the layer of antibodies is selected from the group consisting of IGF1R, Her2, EpCAM, and EGFR, and wherein the cellular target comprises a breast cancer cell. 
     
     
       8. The method of  claim 1 , wherein altering the surface provides a conductivity of the thin film that is proportional to the presence of the cellular target in the bodily source. 
     
     
       9. The method of  claim 1 , wherein altering the surface comprises annealing the substrate after patterning the thin film. 
     
     
       10. The method of  claim 1 , wherein altering the surface comprises annealing the substrate after forming the thin film of CNT's. 
     
     
       11. The method of  claim 10 , wherein annealing the substrate comprises annealing the substrate at a temperature of about 200 degrees Celsius to about 400 degrees Celsius. 
     
     
       12. The method of  claim 10 , wherein annealing the substrate comprises annealing the substrate at a temperature of at least about 300 degrees Celsius. 
     
     
       13. The method of  claim 1 , wherein altering the surface comprises at least one of chemical treatment, oxygen plasma treatment, or infrared heating. 
     
     
       14. The method of  claim 1 , further comprising forming a second sensor on the substrate that has a second biofunctional pad with a hydrophobic surface, wherein altering the surface of the first biofunctional pad is performed without altering the surface of the second biofunctional pad. 
     
     
       15. A method of detecting cellular targets in a bodily source, the method comprising:
 placing a bodily source on a biofunctional pad of a sensor made from the method of  claim 1 , wherein-antibodies associated with a cellular target are disposed on the biofunction pad; and 
 measuring the conductivity of the thin film using a plurality of conductive contacts electrically coupled to the thin film, whereby the conductivity of the thin film is indicative of the presence of the cellular target in the bodily source. 
 
     
     
       16. The method of  claim 15 , wherein the cellular target comprises a cancer cell, and wherein the bodily source comprises a drop of blood. 
     
     
       17. The method of  claim 16 , wherein the antibodies are selected from the group consisting of IGF1R, Her2, EpCAM, and EGFR, and wherein the cellular target comprises a breast cancer cell. 
     
     
       18. The method of  claim 15 , further comprising placing the bodily source on a plurality of biofunctional pads, each comprising a thin film of CNT's upon which is disposed antibodies selected from among a plurality of antibody types associated with the cellular target such that the bodily source may be tested against a plurality of antibody types to detect different markers potentially associated with the cellular target. 
     
     
       19. The method of  claim 15 , wherein the biofunctional pad has a hydrophobic surface, and wherein the conductivity of the thin film is inversely proportional to the presence of the cellular target in the bodily source. 
     
     
       20. The method of  claim 15 , wherein the biofunctional pad has a hydrophilic surface, and wherein the conductivity of the thin film is proportional to the presence of the cellular target in the bodily source.